Conventionally, it has been widely employed a medical tube to be inserted into a portion of a living body such as a lumen, which has a layer with lubricity (lubricant layer) on the surface of an insertion member to be inserted into a living body. It is considered that forming such a layer reduces resistance of contact between the insertion member inserted into the living body and the living body, which makes it possible to improve insertability of the medical tube and alleviate distress in a patient and damage to the body of the patient.
In what follows, taking as examples treatments for lacrimal duct obstruction, intravascular disease, and the like in which a treatment tube with the lubricant layer may be used, background arts of lacrimal duct tube and occlusion catheter for use in these treatments and the like will be described.
First, the lacrimal duct tube will be described. The lacrimal duct tube is a treatment tube for use in treatment of lacrimal duct obstruction resulting in epiphora.
Treatment methods for lacrimal duct obstruction include: (i) probing by a lacrimal duct bougie, (ii) placement of a lacrimal duct tube; (iii) dacryocystorhinostomy (DCR); (iv) lacrimal canaliculoplasty; (v) nasolacrimal duct plasty; (vi) lacrimal caruncle moving surgery, and the like.
The (i) probing by a lacrimal duct bougie is intended to insert a narrow tube called bougie into a lacrimal duct to open an obstructed site and reconstruct a flow path for a lacrimal fluid. The (ii) lacrimal duct tube to be used after that is a lacrimal duct intubation instrument to be placed to keep the flow path and reconstruct tissues. These treatments are conducted as first treatments in many cases due to their ease of execution and minimal invasiveness.
The (iii) dacryocystorhinostomy (DCR), (iv) lacrimal canaliculoplasty, (v) nasolacrimal duct plasty, and (vi) lacrimal caruncle moving surgery are highly effective but relatively invasive because of the need for creation of incisions in a patient's face or drilling holes in bones, and thus are conducted as a last resort.
As a lacrimal duct tube used in (ii), a so-called nunchaku-shaped lacrimal duct tube is widely available (Patent Document 1). The nunchaku-shaped lacrimal duct tube includes a tube and a pair of bougies that is inserted from cuts at both sides of the tube, and the bougies are operated to guide the lacrimal duct tube into a lacrimal duct and place the tube there. As shown in FIG. 2, a lacrimal duct is formed by lacrimal punctum (21 and 22), lacrimal canaliculus (23 and 24), a lacrimal sac (26), a nasolacrimal duct (27), and others. The nunchaku-shaped lacrimal duct tube is inserted into the lacrimal duct.
According to a conventionally and commonly used method for placement of a lacrimal duct tube, it is necessary to fumble for intra-lacrimal duct operations. The bougies in the lacrimal duct tube are blindly operated, and it is thus difficult to correctly insert the tube into a curved or obstructed lacrimal duct. If an operator feels large resistance at insertion of the tube, he/she cannot easily determine whether the resistance results from friction between a wall of an obstructed site in the lacrimal duct and the lacrimal duct tube, or results from the bougie's breaking through the lacrimal duct tube, or results from formation of a temporal path (making a hole in a portion other than the lacrimal duct), or the like, and he/she actually forms a false passage in many cases.
In recent years, to avoid such a situation, there has been increasingly populated an operation of inserting a lacrimal duct tube into a lacrimal duct while visually checking the inside of the lacrimal duct using a lacrimal endoscope, thereby allowing the lacrimal duct tube to be correctly inserted into an obstructed lacrimal duct while checking an insertion position. In addition, as treatments using an endoscope have been performed on increasing occasions, it has been found that there has been a difference in treatment results between the case of correctly placing the lacrimal duct tube in a lacrimal duct and the case of placing the lacrimal duct tube in a temporal path. Thus, there has been re-acknowledged the importance of correctly placing the lacrimal duct tube. As described above, although it has been recognized that operations using a lacrimal endoscope are very effective in insertion of the lacrimal duct tube into a lacrimal duct, lacrimal endoscopes are installed in a limited number of hospitals under the present circumstances, for a reason that the devices are expensive and the like.
In addition, to place the lacrimal duct tube in an easy and correct manner, there have been suggested lacrimal duct tube that have a coating for imparting lubricity to the surface of the tube as an insertion member to reduce resistance at time of insertion and improve insertability (refer to Patent Document 2 and Non-patent Document 1). However, using the coating described in Patent Document 2 or Non-patent Document 1 has not necessarily realized sufficient insertability and the like in practical use under the present circumstances.
Next, the occlusion catheter will be described. The occlusion catheter is a medical catheter for use in, for example, (i) obstruction of a blood vessel in the event of rupture of a thoracic or abdominal aortic aneurysm, (ii) interruption of blood flow for drug administration to an intravascular lesion area, (iii) temporary hemostasis before or during surgery, (iv) various cardiac function tests such as measurement of heartbeat pressure by adjustment of blood flow, (v) balloon occlusion test at which cerebral blood vessels are temporarily obstructed to measure spare ability of cerebral blood flow, and the like (as an example, refer to Patent Document 3). The occlusion catheter includes a long tube, a balloon capable of inflation and contraction in the vicinity of a distal-side end portion, and a hub at a proximal-side end portion. Via the hub, a fluid is injected into the balloon or removed from the balloon to inflate or contract the balloon. By inflating the balloon in a blood vessel, it is possible to obstruct the blood vessel and control a blood flow.
As in the foregoing, the occlusion catheter is inserted into a thoracic aorta, abdominal aorta, cardiac blood vessel, cerebral blood vessel, or the like for treatment or investigation of a lesion area. In that case, the occlusion catheter is inserted from a blood vessel in a thigh, elbow, or wrist such that the balloon is positioned near a lesion area in a heart, brain, or the like. At that time, the operator needs to operate a portion of the catheter outside the body to move the occlusion catheter by a certain distance within the bent blood vessel. However, it is not easy to guide the long tube by in-vitro operations to a desired site within the bent blood vessel. Thus, for improving insertability of the catheter, in general, the long tube is made softer in the axial direction continuously or stepwise with increasing proximity to the distal side or a lubricant layer is provided on the surface of the tube to reduce resistance at time of insertion.
Meanwhile, there has been suggested, as a surface coating with excellent lubricity and durability, a specific coating composition with lubricity in wet conditions to be applied to the surface of a base material of a medical instrument, and a coating method using the coating (refer to Patent Document 4). By using the specific coating composition, it can be expected that the tube is improved in insertability. However, there remains the possibility that the coating partially comes off of the surface when the catheter is placed in a living body for a long period of time or when the catheter is inserted by a certain distance during passage through a bent portion of a blood vessel or the like. Thus, further improvement in durability is expected, for example, for application of the coating to medical instruments such as a lacrimal duct tube that is to be placed in a living body for a long period of time and an occlusion catheter that is to be moved by a certain distance within a bent blood vessel, for example.